COUNTER CURRENT DISPERSION, SECONDARY CONTACT AND SPECIATION IN LENOKS OF THE GENUS BRACHYMYSTAX

Genetic divergence between two forms of lenok was examined on the basi s of electrophoretic study of 15 enzymes coded for by about 30 gene lo ci. The genetic distances between different populations are: D = 0,000 - 0,097; DBAR = 0,050 for the sharp-spouted form; D = 0,000 - 0,139; DBAR = 0,067 for the blunt-spouted form. This value between two forms is: D = 0,042 - 0,195; DBAR = 0,103. In all regions of sympatry two fo rms are reproductively isolated. Didderent hypotheses about the origin of two forms are discussed. The monophyletic origin of two forms is c onfirmed. It is possible to recognize two forms as two biological spec ies. Based on the gene diversity analysis, we regard the genetic aspec ts of conservation of the two forms.